Powered by a Qualcomm 1 GHz Snapdragon processor, which Google says is ideal for running multiple apps at the same time, the 11.5mm thick handset also features a 3.7in 480x800-pixel AMOLED screen.

The Google Nexus One

Google has also voice-enabled every text field on the phone, so as well as being able to speak their search queries, users can also speak emails, tweets or even Facebook status updates.

The voice recognition also works in conjunction with GPS to allow users to search for a service or shop, and then get turn-by-turn directions to that service.

The Google Nexus One weighs just 130g, which Google described as "no heavier than a keychain Swiss Army knife". It also has a 5Mp camera with LED flash and video capture capabilities, one-click upload to Picasa and YouTube, Bluetooth 2.0 connectivity and and an accelerometer.

Like the G2, the Nexus One has a trackball that features a multi-coloured LED, which can be personalised to notify users of new emails, messagings, calls etc, and Facebook.

Personalisation is a strong theme of the handset. Google revealed that it has added five more panels to allows users to customise the home screen with widgets that suit them, as well as allowing the back of the device to be engraved.

Google also revealed the Nexus One has a light and proximity sensor, which adjusts the screen brightness during use to reduce battery drain.

Users will also benefit from active noise cancellation, two microphones and 'Live wallpapers' that are interactive and respond to touches to the screen. However, there was no mention of multi-touch capabilities, like Apple's iPhone.

Google vice president Mario Caros said the handset marks "the next stage of the evolution of Android".

"Nexus One is an example of what's possible through mobile phones on Android."

"It pushes limits of what a phone can be and embodies HTC experience. Congratulations to Andy Rubin and Android team," added Peter Chou, CEO of HTC.

The Nexus One will be available through a Google-hosted webstore. Users can either purchase the handset SIM-free, or on a contract from T-Mobile and Verizon in the US and Vodafone in the UK.

The Google-hosted webstore

The Google Nexus One is priced at $529 (£331) sim-free in the US. Pricing for the UK has yet to be released. Google said it planned to offer more handsets on other operators in the future.

Google also unveiled a new app, Google Earth for Android, which will hit Android Market later this year and offers mobile phones the same functions as desktop users of the service.